- Lewis acid-promoted α-hydroxy β-dicarbonyl to α-ketol ester rearrangement
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The decarbomethoxylation reaction of a substituted α-hydroxy-α-carbomethoxy pentacyclic substituted ketone, used as an advanced intermediate in the synthesis of the alkaloid aspidophytine, can be effected by heating with MgI2 in CH3CN. The reaction was shown to proceed by a novel α-hydroxy β-dicarbonyl to α-ketol ester rearrangement. It was possible to isolate a carbonate intermediate in 75% yield, thereby providing support for the proposed pathway.
- Hong, Xuechuan,Mejía-Oneto, José M.,Padwa, Albert
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Read Online
- Synthesis of dimethyl adipate from cyclopentanone and dimethyl carbonate over solid base catalysts
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A facile route for the synthesis of dimethyl adipate (DAP) from cyclopentanone and dimethyl carbonate (DMC) in the presence of solid base catalysts has been developed. It was found that the intermediate carbomethoxycyclopentanone (CMCP) was produced from cyclopentanone with DMC in the first step, and then CMCP was further converted to DAP by reacting with a methoxide group. The role of the basic catalysts can be mainly ascribed to the activation of cyclopentanone via the abstraction of a proton in the α-position by base sites, and solid bases with moderate strength, such as MgO, favor the formation of DAP.
- Wu, Dudu,Chen, Zhi,Jia, Zhenbin,Shuai, Li
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Read Online
- Does the Dieckmann Condensation Occur in the Gas Phase ?
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Burinsky and Cooks have reported that deprotonated dimethyl adipate eliminates methanol via a gas-phase Dieckmann condensation.This is in contrast to the behaviour of simple methyl ester enolates which lose MeOH by a different mechanism, e.g.MeOCOCHCH2R -> -> O=C=CHCHR + MeOH.Evidence is presented which supports the Dieckmann mechanism for adipates.For example, MeOCOC(Me)CH2CH2CD(Me)CO2Me should eliminate MeOD in a Dieckmann condensation, but MeOH by the alternative mechanism outlined above.Experimentally , MeOD is lost exclusively.Similarly, MeOCOCDCH2CH2C(Me)2CO2Me also loses MeOD, consistent with a Dieckmann process
- Raftery, Mark J.,Bowie, John H.
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Read Online
- The profound effect of the ring size in the electrocyclic opening of cyclobutene-fused bicyclic systems
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Fused cyclobutenes, prepared by the photocycloaddition of propargyl alcohols to cyclic anhydride chromophores, undergo facile thermochemical ring opening to fused γ-lactones. The size of the fused ring profoundly influences the temperature that is required to facilitate the ring opening (from 50°C to 180°C) and the nature of the product that is formed. Our studies provide new insights into the mechanistic course of these reactions and have been extended to facilitate the preparation of lactams fused to medium-sized rings.
- Ralph, Michael J.,Harrowven, David C.,Gaulier, Steven,Ng, Sean,Booker-Milburn, Kevin I.
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Read Online
- Catalytic TMSCl promoted powerful aldol addition and Claisen condensation mediated by TiCl4/Bu3N agent: Comparison and evaluation with the Mukaiyama aldol addition
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TMSCl catalyst (0.05 equiv) significantly promoted the TiCl4/Bu3N-mediated direct cross aldol additions of sterically crowded ketones and α-hetero substituted ketones, and also the direct Claisen condensation between methyl esters.
- Yoshida, Yoshihiro,Matsumoto, Noriaki,Hamasaki, Ryota,Tanabe, Yoo
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Read Online
- Highly Selective Difluoromethylations of β-Keto Amides with -TMSCF 2Br under Mild Conditions
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Without employing any transition metal and other additives, efficient methods for selective difluoromethylations of β-keto amides with TMSCF 2 Br reagent have been developed under mild conditions. This protocol allows a convenient access to various α-difluoromethyl β-keto amides with excellent yields (up to 93%) and high carbon/oxygen (C/O) regioselectivities (up to 99:1). The C/O selectivity of β-keto amides could be easily reversed and controlled by simply changing the base. This protocol can be easily scaled-up and the C-difluoromethylation product could be reduced into CF 2 H-containing amino alcohol derivatives. Moreover, the first enantioselective electrophilic difluoromethylation of β-keto amides has been achieved by phase-transfer catalysis.
- Chen, Pengli,Fu, Yang,Hu, Yanqin,Wang, Shuaifei,Wang, Yakun,Zhang, Conghui,Zhang, Mingwei,Zhao, Ting
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supporting information
p. 1123 - 1130
(2021/06/18)
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- INHIBITORS OF LYSINE BIOSYNTHESIS VIA THE DIAMINOPIMELATE PATHWAY
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The present invention relates to compounds that have the ability to inhibit lysine biosynthesis via the diaminopimelate pathway in certain organisms. As a result of this activity these compounds can be used in applications where inhibition of lysine biosynthesis is useful. Applications of this type include the use of the compound as herbicides and/or anti-bacterial agents.
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Paragraph 0271
(2020/01/24)
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- A substituted phenylacetic acid derivatives (by machine translation)
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The invention belongs to the field of drug synthesis, relates to a substituted phenylacetic acid derivatives, in particular to the preparation of 2 - [4 - (2 - methyl oxygen fifth heavenly stem) hydrocinnamic acid] preparation method. If nitrile alkylation reaction include alkylation reaction, reaction or ester alkyl [...] reaction to prepare the intermediate type II - 2 or type II - 2' compound, After the hydrolytic reaction or oxidation reaction preparation to obtain the product. The invention relates to the alkylation reaction without additional solvent, is a more industrialization of the advantages of the line. (by machine translation)
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Paragraph 0041; 0042
(2019/04/18)
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- Synthesis method of 2-methyl oxycyclopentane carboxylate
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The invention discloses a synthesis method of 2-methyl oxycyclopentane carboxylate. Dimethyl adipate used as a main raw material reacts with alkaline for intramolecular cyclization, and then methanolis eliminated for one minute to obtain a target compound. The whole synthesis process simplifies the operation, and produces a relatively small amount of wastewater. According to the synthesis method,the condensation reaction and the elimination reaction are completed by only one type of alkali, so that the number of material varieties is reduced, and the operation efficiency is improved. No prohibited chemicals such as samarium diiodide and mercury are used in the synthesis method; no strong alkali such as butyl lithium is used either; ultralow temperature is not required, so that the production cost is reduced; and in a word, the synthesis method disclosed by the invention has the following characteristics of mild reaction conditions, simple technological operation, environmental friendliness, low cost and high yield.
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Paragraph 0025; 0040-0063
(2018/09/13)
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- Methoxycarbonyl migration in 3-methylene-1,4-cyclohexadienes. An extension of the von Auwers rearrangement This article is dedicated to Professor Neil Garg, recipient of the 2015 Tetrahedron Young Investigator award
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Upon heating, 3-methylene-1,4-cyclohexadienes possessing an alkoxycarbonyl substituent in position 6 undergo rearrangement and concomitant aromatization to give the corresponding arylacetates. This transformation represents a modification of the von Auwers rearrangement and proceeds by a radical chain mechanism. The intermediate alkoxycarbonyl radical can be intercepted allowing further useful synthetic variations.
- Boumediene, Mehdi,Guignard, Rapha?l F.,Zard, Samir Z.
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p. 3678 - 3686
(2016/06/06)
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- Trimethylchlorosilane-Mediated Mild α-Chlorination of 1,3-Dicarbonyl Compounds Promoted by Phenyliodonium Diacetate
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Trimethylchlorosilane was used as chlorine source for the α-chlorination of 1,3-dicarbonyl compounds with phenyliodonium diacetate as oxidant at room temperature. The reaction allows the selective synthesis of α-monochlorinated products from different kinds of 1,3-dicarbonyl compounds in good yield. The potential possibility of this conversion for bromination has also been investigated.
- Chong, Siying,Su, Yingpeng,Wu, Lili,Zhang, Weigang,Ma, Junyan,Chen, Xiaowei,Huang, Danfeng,Wang, Ke-Hu,Hu, Yulai
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supporting information
p. 1359 - 1370
(2016/05/02)
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- Synthesis and evaluation of new coumarin derivatives as potential atypical antipsychotics
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In this paper, we report the synthesis of novel, potential antipsychotic coumarin derivatives combining potent dopamine D2, D3 and serotonin 5-HT1A, 5-HT2A receptors properties. We describe the structure activity relationship that leads us to the promising derivative: 7-(4-(4-(6-fluorobenzo[d]isoxazol-3-yl)piperidin-1-yl)butoxy)-6-methyl-2, 3-dihydrocyclopenta[c]chromen-4(1H)-one 27. The unique pharmacological features of compound 27 are a high affinity for dopamine D2, D3 and serotonin 5-HT1A, 5-HT2A receptors, together with a low affinity for H1 receptor (to reduce the risk of obesity under chronic treatment). In animal models, compound 27 inhibited apomorphine-induced climbing and MK-801-induced hyperactivity without observable catalepsy at the highest dose tested. In particular, compound 27 was more potent than clozapine.
- Chen, Yin,Lan, Yu,Wang, Songlin,Zhang, Heng,Xu, Xiangqing,Liu, Xin,Yu, Minquan,Liu, Bi-Feng,Zhang, Guisen
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p. 427 - 439
(2014/02/14)
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- ALICYCLIC[C] BENZOPYRONE DERIVATIVES AND USES THEREOF
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Disclosed are alicyclic[c]benzopyrone derivatives and use thereof. The alicyclic[c]benzopyrone derivatives are compounds represented by formula I or their salts. The present compounds not only significantly improve high activity induced by MK-801, but also effectively improve clambering symptom induced by Apomorphine and do not cause EPS within effective dose. These in vitro targets and in vivo pharmacological models are closely related to diseases of the nervous system caused by dopamine dysfunction, especially schizophrenia. Therefore the present compounds can be used for the treatment of central nervous system diseases, especially schizophrenia. ED50 is lower and effect is stronger in two animal models i.e. high activity induced by MK-801 and clambering symptom induced by Apomorphine, while ED50 is higher and therapeutic index is greater in animal models of catalepsy.
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Paragraph 0075
(2014/06/25)
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- ALICYCLIC[C]BENZOPYRONE DERIVATIVES AND USES THEREOF
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Disclosed are alicyclic[c]benzopyrone derivatives and use thereof. The alicyclic[c]benzopyrone derivatives are compounds represented by formula I or their salts. The present compounds not only significantly improve high activity induced by MK-801, but also effectively improve clambering symptom induced by Apomorphine and do not cause EPS within effective dose. These in vitro targets and in vivo pharmacological models are closely related to diseases of the nervous system caused by dopamine dysfunction, especially schizophrenia. Therefore the present compounds can be used for the treatment of central nervous system diseases, especially schizophrenia. ED50 is lower and effect is stronger in two animal models i.e. high activity induced by MK-801 and clambering symptom induced by Apomorphine, while ED50 is higher and therapeutic index is greater in animal models of catalepsy.
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Paragraph 0037
(2014/07/08)
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- Azidation of β-keto esters and silyl enol ethers with a benziodoxole reagent
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The efficient azidation of β-keto esters and silyl enol ethers using a benziodoxole-derived azide transfer reagent is reported. The azidation of cyclic β-keto esters could be achieved in up to quantitative yields in the absence of any catalyst. In the case of less reactive linear β-keto esters and silyl enol ethers, complete conversion and good yields could be obtained by using a zinc catalyst.
- Vita, Maria Victoria,Waser, Jerome
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supporting information
p. 3246 - 3249
(2013/07/26)
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- Synthesis, preliminary biological evaluation and molecular modeling of some new heterocyclic inhibitors of TACE
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Central heteroaryl ring analogues belonging to a series of potent hydroxamate TACE inhibitors were synthesized. The TACE inhibitory activities of these compounds were evaluated by in vitro WBA and in silico molecular modeling studies using crystal structure of human TACE. Compound 14 showed very good in vitro inhibition, supported by the in silico docking studies.
- Sengupta, Prabal,Puri, Chetan S.,Chokshi, Hemant A.,Sheth, Chetana K.,Midha, Ajay S.,Chitturi, Trinadha Rao,Thennati, Rajamannar,Murumkar, Prashant R.,Yadav, Mange Ram
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experimental part
p. 5549 - 5555
(2011/12/15)
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- Ambient carboxylation on a supported reversible CO2 carrier: Ketone to β-keto ester
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A reversible CO2 carrier (RCC) has been developed to perform carboxylation of ketone to β-ketoester under ambient CO2 pressure and temperature. RCC has been synthesized by immobilizing 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) on methylhydrosiloxane support and reacting with CO2 with 100% degree of functionalisation. RCC is found to be recyclable and shows retention of activity in 5 recycles. CO2 absorption under ambient temperature and desorption at 120°C renders the material suitable for carrying out carboxylation reactions at 25°C with excellent yields. The yield of the reaction can reach up to 100% with TON 200 in 4 h. The extent of the reaction primarily depends upon enol content of the substrate. β-Ketoacid produced during the reaction can be isolated and converted to its corresponding methyl ester derivative by reacting with methyl iodide.
- Beckman, Eric J.,Munshi, Pradip
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experimental part
p. 376 - 383
(2011/04/17)
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- A systematic study of the solid state and solution phase conformational preferences of β-peptides derived from C(3)-alkyl substituted transpentacin derivatives
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The solid state and solution phase conformational preferences of a homologous series of β-peptides derived from a range of 2-amino-3-alkylcyclopentanecarboxylic acid residues have been investigated using a variety of spectroscopic and crystallographic techniques. These studies indicate that C(3)-alkyl substitution trans to the amino group on the cyclopentane backbone is tolerated by the established 12-helix secondary structural preference of the parent pentamer and hexamer derived from 2-aminocyclopentanecarboxylic acid (transpentacin) residues in both the solid state and solution phase. Evidence for the alternative turn type conformation identified for the C(3)-unsubstituted tetramer was not observed in the C(3)-alkyl substituted derivatives, consistent with the alkyl substituent anti to the amino functionality destabilising this motif. These results suggest that oligomers based around the transpentacin scaffold may be amenable to further elaboration at C(3) anti to the amino group with retention of the secondary structure.
- Abraham, Elin,Claridge, Timothy D.W.,Davies, Stephen G.,Odell, Barbara,Roberts, Paul M.,Russell, Angela J.,Smith, Andrew D.,Smith, Lorna J.,Storr, Helen R.,Sweet, Miles J.,Thompson, Amber L.,Thomson, James E.,Tranter, George E.,Watkin, David J.
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experimental part
p. 69 - 100
(2011/04/18)
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- Highly enantioselective synthesis of β-amino acid derivatives by the lewis base catalyzed hydrosilylation of β-enamino esters
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A study was conducted to demonstrate highly enantioselective synthesis of β-amino acid derivatives by the Lewis base catalyzed hydrosilylation of βenamino esters. It was found that these catalyst and its analogue displayed excellent activities and enantioselectivities in promoting hydrosilylation of N-aryl β-enamino esters. N-picolinoylpyrrolidine derivatives and N-picolioylephedrine were also evaluated in hydrosilylation of (Z)-methyl 3-phenyl-3-(phenylamino)acrylate. The generality of the Lewis base organocatalyzed hydrosilylation of various β-enamino esters were examined under the optimized conditions. It was observed that the catalytic system exhibited a high sensitivity to the N-substituents, while all the N-aryl β-enamino esters underwent the hydrosilylation smoothly to give corresponding β-amino esters.
- Zheng, Hong-Jie,Chen, Wen-Bing,Wu, Zhi-Jun,Deng, Jin-Gen,Lin, Wen-Qing,Yuan, Wei-Cheng,Zhang, Xiao-Mei
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supporting information; experimental part
p. 9864 - 9867
(2009/10/02)
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- Catalytic reactions of samarium(II) iodide
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A system for in situ regeneration of SmI2 from SmI3 is described which allows the annulation of ketones to γ-lactones, the deoxygenation of oxiranes to olefins and radical π-cyclization to be conducted with 10 mole % SmI2.
- Corey,Zheng, Guo Zhu
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p. 2045 - 2048
(2007/10/03)
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- TiCl4/Bu3N/(catalytic TMSOTf): Efficient agent for direct aldol addition and claisen condensation
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TiCl4/Bu3N conducts highly efficient cross aldol additions between different ketones and between ketones and aldehydes, in good to excellent yields with high syn-stereoselectivities. As an extension, direct Claisen condensation between methyl esters was also promoted by TiCl4/Bu3N with 0.05 equiv of TMSOTf co-catalyst.
- Yoshida, Yoshihiro,Hayashi, Ryosuke,Sumihara, Hiromasa,Tanabe, Yoo
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p. 8727 - 8730
(2007/10/03)
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- Direct Observation of α-Oxo Ketenes from the Photolysis of α-Diazo β-Diketones
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Monitoring by IR spectroscopy of the broad-band irradiation of the symmetrically substituted 2-diazocyclohexane-1,3-dione (11), 3-diazopentane-2,4-dione (19), and 4-diazo-2,2,6,6-tetramethylheptane-3,5-dione (24) in Ar matrices at 12 K showed the formation of 2-carbonylcyclopentanone (s-Z-12), acetyl(methyl)ketene (s-E-20), and tert-butyl(pivaloyl)ketene (s-E-25), respectively, in less than 10 min.On increasing the photolysis time to >3 h, the α-oxo ketenes 12, 20, and 25 decarbonylated to the corresponding oxocarbenes which underwent Wolff rearrangement to carbonylcyclobutane (15), dimethylketene (23), and di-tert-butylketene (28), respectively.The reaction of 2-carbonylcyclopentanone (12) with CH3OH was monitored by IR spectroscopy.Thus, it was found that the reaction started at ca. 100 K and was essentially complete at 140 K, involving the initial formation of the enol form (9) of methyl 2-oxocyclopentanecarboxylate.
- Leung-Toung, Regis,Wentrup, Curt
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p. 4850 - 4858
(2007/10/02)
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- A FACILE RING ENLARGEMENT
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A series of functionalized seven to eight membered rings was prepared by a ring expansion technique involving intramolecular aldol condensation and subsequent retro-aldol cleavage.
- Xie, Zhuo-Feng,Suemune, Hiroshi,Sakai, Kiyoshi
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p. 987 - 992
(2007/10/02)
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- THE SELECTIVE CLAISEN AND DIECKMANN ESTER CONDENSATION PROMOTED BY DICHLOROBIS(TRIFLUOROMETHANESULFONATO)TITANIUM(IV)
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Inter and intramolecular condensations (the Claisen and the Dieckmann condensations) between ester functions have been performed by the combined use of dichlorobis(trifluoromethanesulfonato)titanium(IV) (=dichlorobis(triflato)titanium(IV)) and tertiary amine under mild reaction conditions.These results led to the development of the selective (crossed) Claisen and Dieckmann ester condensation between methoxymethyl ester and methyl ester, in that, dichlorobis(triflato)titanum(IV) contribute to control the direction of the reaction.
- Tanabe, Yoo
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p. 1917 - 1924
(2007/10/02)
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- SYNTHESIS OF STABLE ANALOGUES OF TXA2
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Intramolecular aldol condensations and intramolecular Lewis acid-catalysed alkylations are used in approaches to substituted bicyclononanes and bicyclooctanes, specifically the oxo esters ( 7 ), ( 8 ), and ( 9 ).A ring expansion to a cycloheptane derivative is observed on treatment of the cyclopentyl derivative ( 18 ) with acid, and the bicyclodecane and bicyclononane derivatives ( 34 ) and ( 36 ) are obtained from the prenyl derivatives ( 30 ) and ( 35 ) respectively.The oxo esters ( 7 ), (8 ), and ( 9 ) are converted into the stable TXA2 analogues ( 10 ), ( 11 ), and ( 12 ) respectively, by a series of reactions which involve stereospecific functionalisation of their ketone and ester groups.
- Evans, Elizabeth H.,Hewson, Alan T.,March, Lorraine A.,Nowell, Ian W.,Wadsworth, Alan H.
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p. 137 - 150
(2007/10/02)
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- The Crossed Claisen Ester Condensation Mediated by Titanium(IV) Bistriflate
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The crossed Claisen ester condensation between methoxymethyl ester and methyl ester promoted by the combined use of titanium(IV) bistriflate and tertiary amine has been established.
- Tanabe, Yoo,Mukaiyama, Teruaki
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p. 1813 - 1816
(2007/10/02)
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- DICHLORO-BIS(TRIFLUOROMETHANESULFONATO)TITANIUM(IV) AS AN EFFECTIVE PROMOTER IN THE CLAISEN ESTER CONDENSATION
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Inter- and intra-molecular condensation (the Claisen and the Dieckmann condensations) between ester functions have been effected by the combined use of dichloro-bis(trifluoromethanesulfonato)titanium(IV) and tertiary amine under mild conditions.
- Tanabe, Yoo,Mukaiyama, Teruaki
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p. 1867 - 1870
(2007/10/02)
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- Synthesis of Methyl Esters by Titanate-catalyzed Transesterifications
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The low solubility of tetramethyl titanate has so far prevented the laboratory use of titanate-catalyzed transesterifications with formation of methyl esters.Two procedures are described here, which allow the application of this exceedingly mild method to the synthesis of methyl esters: one uses methyl propionate/Ti(OEt)4, the other one uses methanol/Gly-Ti, a new type of catalyst, prepared from Ti(OEt)4/ethylene glycol 2:1.
- Schnurrenberger, Peter,Zueger, Max F.,Seebach, Dietrich
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p. 1197 - 1201
(2007/10/02)
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- Acylations of Thiol Ester Enolate Anions
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The synthetic utility of thiol ester anions has been explored.Claisen condensations of thiol esters with isopropylmagnesium bromide base proceed in good yield.The Dieckmann reaction of diethyl thiolpimelate to form a six-membered ring proceeds in 74 percent yield, but the corresponding reaction of diethyl thioladipate to provide a five-membered ring gives only 26 percent yield.Neither alkylation of ethyl thiolacetate nor a Michael-type adduct with methyl vinyl ketone could be achieved.The mechanism of the Claisen condensation as it applies to thiol esters is discussed.
- Wilson, G. Edwin,Hess, Arye
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p. 2766 - 2772
(2007/10/02)
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- Reactions of Dialkylamide Metal Salts with Diesters
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The use of diethylamide magnesium bromide, diisopropylamide magnesium bromide, diethylamide lithium and diisopropyllithium in intermolecular condensation of diesters (II) leading to long open chain β-keto-esters (IV) and in intramolecular condensation of diesters (II) leading to cyclic β-keto-esters (V) has been investigated.
- Singh, Pramod Kumar,Rajeswari, K.,Ranganayakulu, K.
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p. 823 - 824
(2007/10/02)
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